The feeding of a liquid enteral nutritional product from a container, such as a bottle or a plastic bag with a bottom outlet connecting to a drip chamber and the latter to a flexible tubing, or lumen, leading to a nasogastric tube or a feeding tube inserted through a gastrostomy or a jejunostomy, by gravity flow or aided by a peristaltic pump, is well known. The liquid enteral nutritional product may be aseptically processed or terminally retorted before use, and may be supplied in a pre-filled, ready-to-hang container, or placed in such a container by a caregiver. However, problems sometimes arise that the flow of the liquid enteral nutritional product is not begun because of a mechanical malfunction or distraction of the caregiver and this is not noted for a time. Sometimes the product is misdirected for similar reasons. A still further problem arises in that the nutritional product may be refluxed from the stomach or small bowel of the patient for any of various reasons of indigestion or overfeeding, and may find its way into the lungs. In such an event, special care of the patient is needed, and the problem usually becomes more serious if it is not noted fairly promptly.
In each of these instances it would ordinarily be very helpful if the presence of the liquid enteral nutritional product in an out-of-place location external to the stomach or intestines of the patient were more easily detectable. One way to more easily detect the presence of a liquid enteral nutritional product would be to make it visible by dissolving in the product a suitable physiologically acceptable marker dye. However, this may not be undertaken lightly outside of specially equipped facilities, such as a manufacturing facility, because information is usually lacking concerning compatibility of specific dyes, with various specific nutrients or medicaments that may be present in the liquid nutritional product, during heat sterilization and/or subsequent storage of the product when mixed with dye. If the marker dye is placed in solution prior to sterilization of the product there is the possibility of altering the composition of the product or the color of the dye. Moreover, the process of introduction of a marker dye, such as a food grade dye, after sterilization, may cause loss of sterility, even if certified sterile dyes are used. Thus, care must be taken to avoid contamination of a nutritional product in which organisms might multiply rapidly during storage or transport.
Drug delivery systems have been described and claimed in U.S. Pat. Nos. 4,511,353, 5,318,558 and 5,324,280 in which the drug component to be delivered is stored in a capsule from which it is ejected over time upon osmotic infusion of moisture into the capsule, the drug being carried away from the outside surface of the capsule by a suitable liquid in an intravenous, i.e., parenteral, delivery system, or even, by the device of U.S. Pat. No. 5,318,558, by body fluids upon implantation of the capsule.
In U.S. Pat. No. 5,069,671 there is described a formulation chamber, which may also be a drip chamber, in which various forms of sustained release mechanisms are employed to release a drug or medicament, or other physiologically beneficial component such as a nutrient, within the formulation chamber from which the drug or other component is carried by a suitable liquid into a parenteral delivery system.
The teachings of U.S. Pat. Nos. 4,511,353 and 5,069,671 are directed to intravenous delivery of parenteral compositions, and in the case of the latter patent, includes delivery by infusion through intravenous, intraarterial, intraperitoneal or subcutaneous routes. The osmotic dosage system of U.S. Pat. No. 5,324,280 is concerned with the delivery of drug formulations over time to a biological environment, such as a tissue or organ implant in a mammal, or a stream or tank for marine life. The osmotically driven device of U.S. Pat. No. 5,318,558 is said to be usable to deliver drugs, medicaments and nutrients in a range of environments extending from veterinary medicine to human drug administrations, and to hobby situations such as fish tanks. Again, in the case of human administration, the delivery appears to be by implantation within the tissue or an organ of the patient, followed by action of body fluids upon the osmotic device.
Although the osmotic delivery devices and other forms of sustained release dosage forms have been available for some time, so far as is known, there has been no attempt to utilize such a delivery system to add a marker dye to a liquid enteral nutritional product, with a viscosity up to 300 cps., at the time of administering the product to the gastrointestinal tract of a patient. Liquid enteral nutritional products currently on the market are described in the reference text "Nutrition In Critical Care", Gary P. Zaloga, ed., Mosby--Year Book Inc., St. Louis, Mo., 1994, at Chapter 24, authored by Barbara Hopkins, Part III, "Feeding", pp. 439-467. This reference indicates that complete nutrient compositions contain proteins, carbohydrates, fibers, fats, and vitamins and minerals, in various proportions in an aqueous or aqueous/fat medium. Nutrient compositions for special diets may omit, entirely or in part, one or more classes of these components.